Screening freight cargo containers and the like to detect the presence of threat substances or contraband such as for example narcotics, chemical warfare agents, biological warfare agents, nuclear or radiological agents, ammunitions, toxic industrial chemicals or waste, embargoed or smuggled items such as tobacco, human and/or animal stowaways etc. is common practice. To screen freight screen cargo containers, x-ray imaging systems have commonly been employed to scan the content of such containers and generate images that can be examined to determine if any threat substances exist therein. Unfortunately these imaging systems suffer disadvantages in that they are bulky, expensive and require a skillful operator to interpret the generated images in order to distinguish between non-threat substances such as coffee, sugars, flours, rice shipments etc. and threat substances. Even with a skilled operator, high false alarm rates are common. Also, the use of x-rays to image the content of the freight cargo containers can be damaging to the freight cargo container content and may pose potential hazard to the operators.
Other non-imaging techniques to screen the content of freight cargo containers have been considered. One such non-imaging screening technique involves the use of nuclear probing beams, such as thermal neutron, pulsed neutron, accelerated fast neutron or gamma-ray beams to probe freight cargo containers for the existence of threat substances. The interaction of the probing beams with objects inside the freight cargo containers produces secondary gamma-rays, which are detected by suitable arrays of detectors allowing the nature of the freight cargo container content to be determined. Nuclear quadrupole resonance (NQR) has also been employed to scan freight cargo containers and determine the chemical composition of the freight cargo container content. Unfortunately, these non-imaging screening techniques have low detection limits, are unable to detect the amounts of threat substances in freight cargo containers and suffer inaccuracies due to interference from common non-threat substances. These non-imaging screening techniques also require large, complex and expensive installations and screen freight cargo containers at relatively slow rates.
Other screening techniques have also been considered. For example, U.S. Pat. No. 5,859,362 to Neudorfl et al. discloses a method and device for the detection of vapors of cocaine and associated compounds. The method involves sampling a volume of air suspected of containing cocaine vapors, passing the air through a filtration system that removes any particulate matter and binds vapors of cocaine and associated compounds, if present, for further analysis. A preferred associated compound-vapor is that of ecgonidine methyl ester (EDME), and a marker for the presence of cocaine. The device is comprised of sampling, filtration and vacuum port components that can be attached to a container and a suction source, for the sampling of air.
Canadian Patent No. 2,129,594 to Nacson discloses a device for collecting vapors from particulates of target substances for analysis, in an environment which contains considerable extraneous particulates of greater or less volatility than the particulates of target substances. The device comprises a first metal screen surface for collecting the particulates of the target substances in the environment containing the extraneous particulates; heater means connected to the first metal screen surface for maintaining the first metal screen surface at a sufficiently high temperature to volatilize the particulates of the target substances, but not the less volatile extraneous particulates, thereby creating volatized vapors from the target particulates; and a second metal surface for collecting the volatilized vapors from the target particulates for further analysis.
U.S. Pat. No. 5,395,589 to Nacson discloses an apparatus for preconcentrating trace amounts of organic vapors in a sample of air for subsequent detection. The apparatus comprises a metallic substrate, a thin film of fullerenes deposited on the metallic substrate for adsorbing the organic vapors on the thin film of fullerenes, thereby preconcentrating the organic vapors and an apparatus for heating the metallic substrate to a predetermined optimum temperature for desorbing the vapors from the thin film of fullerenes to form desorbed organic vapors for subsequent detection.
U.S. Pat. No. 7,468,672 to Harden et al. discloses a chemical analysis method for detecting, identifying and reporting contraband, illegal drugs, explosives, toxic chemicals, decaying animal and vegetable matter, and concealed human beings located in secure spaces such as cargo shipping containers. Chemical analysis results are accumulated and added to effect definitive analyses over extended periods of time while the containers are in transit. Individual containers are equipped with a device employing the method. The analysis method consists of accumulation and addition of analytical chemical instrumentation, measurements of trace quantities of target chemical vapors inside of shipping containers while the containers are in transit. Cumulative and additive spectrometric analyses coupled with increased target chemical concentrations, due to chemical vapor build up over the long periods of time that containers are in transit, result in significantly increased electronic signal-to-noise in spectrometric measurements and increased spectrometric signal strengths that are indicative of the presence of target chemicals.
U.S. Pat. No. 7,456,393 to Napoli discloses a device for testing surfaces of a card for the presence of explosives, drugs or other substances of interest. The device includes a slot for receiving the card. Thin metallic wiper blades are disposed in alignment with the slot and wipe over surfaces of the card as the card is passed through the slot. Thus, substances on the surface of the card are transferred to the wiper blade. The wiper blade then is enclosed and rapidly heated to desorb the material retrieved from the card. The enclosure then is placed in communication with a detector to test for the presence of substances of interest.
U.S. Pat. Nos. 7,188,513 and 7,100,424 to Wilson disclose systems, methods and apparatus for detecting concealed security threats by sampling molecules of substances for assessment. Inspection of cargo containers by sampling the air contained therein and then analyzing the sampled air from the container for security threats including chemical, biological, radiological, nuclear, and high-explosive threats is permitted without requiring the modification of the existing container, the movement of the container to a particular inspection site, and without opening the container. Nuclear security threats may also be scanned for with close proximity nuclear radiation detection sensors closely coupled to areas at or near the concealed security threats. In addition, detection of other types of contraband, including illegal substances, embargoed materials and human and/or animal stowaways may also be assessed. The concealed security threat detection system generally includes a detection system comprising a detector array, an air-moving device, and one or more air-sampling devices. The system may be mounted upon a vehicle for mobility, run on tracks, cables and pulleys, telescoping and swiveling arms, etc.
U.S. Reissue Pat. No. RE38,797 to Linker et al. discloses an apparatus and method for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. The main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current therethrough, to promote desorption of particles therefrom during the flow of the carrier gas.
U.S. Pat. No. 5,988,002 to Danylewych-May et al. discloses a hand held sampling method carried out using an apparatus have a handle, a head connected to the handle and a mechanism for retaining a substrate on the head. The substrate is preferably a sheet-form flexible substrate which is mounted so as to present a collection portion thereof for collection of a sample. The substrate is preferably of a dimension so as to be readily fitted into the inlet portion of an analyzer. The apparatus is manipulated so that the collection portion of the substrate traverses surfaces of interest. The substrate is then removed and placed at the inlet of the analyzer for desorption of a sample. The apparatus enables an area to be sampled quickly and efficiently, while keeping a user's hands away from the surface.
U.S. Pat. No. 5,741,984 to Danylewych-May et al. discloses an apparatus for the collection of a chemical sample from the fingers of an individual for subsequent analytical analysis comprising a token having a base and a substrate on the base. The substrate defines an area such that when the token is removed from a token dispenser the fingers of the individual come into contact with the substrate. Sufficient force must be applied by the fingers of the individual to the substrate when the token is removed from the token dispenser that a chemical sample is transferred from the fingers of the individual to the substrate. The token is then presented for analysis. The substrate may be polytetrafluoroethylene or cotton. A token handler for use in association with the token and an analyzer are also disclosed.
U.S. Pat. Nos. 4,580,440 and 4,718,268 to Reid et al. disclose a method of detecting contraband substances in freight cargo containers in which the container is agitated to disturb particulates therein, and air containing such particulates is then sampled and the particulates collected. The collected particulates include naturally occurring particulates which have absorbed vapors of the contraband substance during the entire time that the container has been closed, and also include particulates of the contraband substance itself. The collected particulates are then heated to a temperature above 160° C. to drive off vapors indicative of the contraband substance and the vapors are analyzed in a mass analyzer.
Many techniques have also been developed for screening passengers and their luggage. For example, U.S. Pat. No. 4,909,090 to McGown et al. discloses a portable, hand-held vapor sampling probe for collecting vapors of compounds such as cocaine, heroin, and explosives prior to their desorption and analysis in a vapor detector. Rechargeable batteries power a lamp in the front face of the probe for heating target portions of a sampling surface, a puffer assembly for directing air jets at the target, and a motor for drawing air samples through a collector coil on whose surfaces vapors are trapped. A flexible U-shaped shroud on the front face partially encloses the lamp and collector and helps to regulate air flow over the target and to protect the probe from damage. Upon contact with a surface, the shroud may activate a switch which, together with a second switch on the probe handle and a lamp pyrometer, regulates heating of the target.
U.S. Pat. No. 5,425,263 to Davies et al. discloses an assembly for preferentially separating and collecting particles that are gathered from the surface of an article such as an item of baggage. The assembly features an impactor and a suction anvil that is displaceable from a collection medium. The anvil is displaceable from the collection medium so that the medium may be removed and analyzed for traces of substances such as explosives or narcotics. There is also provided, in combination with the assembly, a vacuum head and conduit for gathering the particles and a suction unit for creating the suction force. The collection medium containing collected particles is moved from the impactor to an analyzer by a stage movement device. The analyzer includes an analysis unit, such as an ion mobility spectrometer, and a displaceable heater anvil.
U.S. Pat. No. 5,476,794 to O'Brien et al. discloses a method of rapidly checking surfaces for the presence of traces of specific compounds such as certain explosives and drugs. A hand-covering such as a cotton glove is used to wipe surfaces to pick up particles of the specific compound which may indicate the presence of larger amounts or previous contact of a surface by a person who has handled the compound. The particles are transferred, unheated, to collection surfaces of a hand-held sample probe by vacuuming of the gloved hand by the battery-operated probe. Heat is then supplied by a source external to the probe to vaporize the particles, and the vapors are analyzed by a suitable technique such as high speed gas chromatography.
U.S. Patent Application Publication No. 2007/0266771 to Goldson et al. discloses a capture system to enable volatiles associated with targeted materials located within a confined environment to be trapped over a period of time to enable the volatiles to be concentrated. The capture system comprises a package having a “surface” which is constructed in a manner that it can be located within a confined environment to trap specific volatiles associated with the targeted materials. The captured volatiles are desorbed from the surface and are analysed and the results compared with known signature volatile profiles from the targeted materials.
Although various techniques for detecting the presence of threat substances are described above, improvements are continually being sought. It is therefore an object of the present invention to provide a novel non-invasive method and system for screening the content of containers for the presence of threat substances.